Circulating internet topic includes half of blue symbol (6)

I believe the answer is:

emblem

I'm a little stuck... Click here to teach me more about this clue!

'symbol' is the definition.
(I know that emblem is a type of symbol)

I cannot understand how the remainder of the clue works.

Can you help me to learn more?

(Other definitions for emblem that I've seen before include "Visible symbol of an abstract idea" , "Symbol or hallmark" , "Symbolic representation on badge etc" , "Badge, token" , "Typifying symbol" .)

I've seen this clue in The Times.

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